1. Field of the Invention:
The present invention generally relates to a resinous composition comprising an aromatic polyester, a phosphite compound and a carboxylic acid metal salt and process for production of shaped articles using the foregoing composition. More specifically, it relates to a resinous composition and process for production of shaped articles therefrom comprising the specified aromatic polyester, the specified phosphite compound and the specified organic carboxylic acid metal salt, which is not only improved in discoloration and processability at the time of molding, but long-term resistancy and durability.
2. Description of the Prior Art:
Aromatic polyester polymers are well-known and various processes have been proposed heretofore; (a) an interfacial polymerzation that admixes aromatic dicarboxylic acid dihalides dissolved in an organic solvent non-soluble in water with bisphenols dissolved in an aqueous alkali solution (Examined patent publication No. 1959/65), (b) a solution polymerization in which aromatic dicarboxylic acids are reacted with bisphenols in the presence of an organic solvent (No. 5599/62), (c) an ester interchange process in which aromatic dicarboxylic acids and bisphenols are heated (Nos. 15247/63 and 28119/68), (d) a process of using phase transfer catalysts, etc. Aromatic polyester polymers so prepared have excellent properties including such as heat resistancy, mechanical and electrical properties, so that those are in a widespread use as polymers per se or compositions including shaped articles, films, fibers and the like.
The polymers used in the present invention may be prepared by various processes as aforesaid. The polymers, nontheless, are inferior in processability and necessitate a high plasticizing temperature and a high injecting pressure, from a viewpoint of an extrusion or injection molding. Those also propose a problem of discoloration, when processed, which can not be neglected. Further, aromatic polyester compounds are normally poor in resistancy to hydrolysis. Those polymers, when exposed to high temperature for a long time, suffer from decomposition of main chains to result in a decrease in molecular weight. This phenomenon inevitably leads to a deterioration in properties such as strength of the shaped articles, and therefore an improvement being expected.
In an attempt to overcome such deficiencies, a variety of processes have been proposed, e.g., use of organic phosphines (Non-examined patent publication No. 102042/76), use of phosphorous compounds (No. 100551/77, 134663/77), use of organic carboxylic acid metal salts (No. 152953/77), conjoint use of organic carboxylic acid metal salts and cyclic phosphites (No. 252954/78), conjoint use of carboxylic acid metal salts/epoxy compounds/phosphorous compounds (No. 104654/78), conjoint use of epoxy compounds and phosphorous compounds (No. 104654/78), conjoint use of expoxy compounds and organic carboxylic acid metal salts (No. 84046/78), treatment with reducing agents (No. 30895/76) and so on. In those prior arts, however, mention is only made as to aromatic polyesters comprising terephthalic acid/isophthalic acid and bisphenol A, and satisfactory results are not expected as far as aromatic polyesters, especially those defined by the following general formula (V) stated later.